An example of a conventional hermetic package (hereafter also referred to simply as “package”) is shown in FIGS. 3A and 3B (refer to Patent Literature 1, for example). FIG. 3A is a front view of the package, and FIG. 3B is a sectional view taken along the line A-A shown in FIG. 3A. In the figures, reference numeral 21 represents a base body, and reference numeral 22 represents a frame body. The base body 21 is made of a metal having good thermal conductivity such as copper-tungsten for example, and, the frame body 22, which is made of a metal such as an iron (Fe)-nickel (Ni)-cobalt (Co) alloy, is disposed in upstanding condition at the outer periphery of the upper main surface of the base body 21. The frame body 22 is attached to the base body 21 by means of brazing with a brazing material such as Ag (silver) solder, or otherwise.
The frame body 22 is fabricated by bending a strip-like metal plate at right angles with respect to its lengthwise direction into a frame shape, butting both end faces of the strip-like metal plate bent in a frame shape within a plane of one side wall, and hermetically bonding the end faces together. A juncture 22a is created when the hook-like or straight end faces are butt-joined to each other, with a brazing material such as Ag solder sandwiched between them, by application of heat.
Moreover, in Patent Literature 1, a concave recess 22b is formed in tandem with the juncture 22a on the outer peripheral wall surface of the frame body 22 in the vicinity of the juncture 22a, and also a convex projection 22c is formed on the inner wall surface thereof opposed to the recess 22b of the outer peripheral wall surface. The recess 22b and the projection 22c act to disperse a tensile stress developed in the frame body 22 due to the difference in thermal expansion coefficient between the frame body 22 and the base body 21, whereby portions forming the juncture 22a can be prevented, to some extent, from being detached each other.